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August 19, 2014

NASA Study Investigates Impact Of Prolonged Spaceflight On The Immune System

by Chuck Bednar

redOrbit Staff & Wire Reports - Your Universe Online

Newly discovered changes to the human immune system that occur during spaceflight could force NASA to address potential health concerns in future six-month to one-year-long manned missions to nearby asteroids or Mars.

Writing in a recent edition of the Journal of Interferon & Cytokine Research, scientists involved with a pair of NASA collaborative investigations suggest that something as innocent as the common cold or a case of the flu could become dangerous during long-term space travel.

In that study, researchers from the Validation of Procedures for Monitoring Crewmember Immune Function (Integrated Immune) and Clinical Nutrition Assessment of ISS Astronauts, SMO-016E (Clinical Nutrition Assessment) focused on changes to the immune system of astronauts onboard the International Space Station.

According to NASA, data generated in the early stages of the Integrated Immune study indicated the distribution of immune cells in the blood of ISS crew members is relatively unchanged during flight. However, the study also found that some cell function becomes significantly reduced while some activity becomes elevated.

In short, the immune system becomes confused. When cell activity becomes depressed (or lower than normal), it means that the body’s defenses are not generating the appropriate responses to potential threats. This could also result in the asymptomatic viral shedding observed in some crew members.

Asymptomatic viral shedding means that latent or dormant pathogens in the body reawaken, but without symptoms of illness reappearing. On the other hand, when activity increases, the immune system overreacts, resulting in increased allergy symptoms and rashes (which have been reported by crew members).

“Prior to the Integrated Immune study, little immune system in-flight data had been collected,” Dr. Brian Crucian, a biological studies and immunology expert working with NASA at the Johnson Space Center in Houston, explained in a statement Monday.

“Previous post-flight studies were not enough to make any determination about spaceflight’s effect on the immune system,” he added. “This in-flight data provided the information we needed to determine that immune dysregulation does occur and actually persists during long-duration spaceflight.”

In a recent collaboration between the space agency’s Integrated Immune and Clinical Nutrition Assessment flight studies, scientists examined the blood plasma of 28 crew members before, during, and after the conclusion of their missions. The researchers were measuring the concentration of the proteins responsible for regulating immunity.

Those proteins, which are known as cytokines, cause immune cells to travel to the site of an infection or injury within a person’s body. They also facilitate cell-to-cell communication, and signal immune cells to activate and mount a defense against invaders – a process usually referred to as inflammation.

As in the changes in cell function discovered in the Integrated Immune study, the data from the Clinical Nutrition Assessment research revealed that ISS crew members also experience changes in blood cytokines that persist during flight. This gives the scientists an idea of what areas of an astronaut’s immune system could be affected during flight, and what factors associated with the environment might be causing those changes.

“Things like radiation, microbes, stress, microgravity, altered sleep cycles and isolation could all have an effect on crew member immune systems,” Dr. Crucian said. “If this situation persisted for longer deep space missions, it could possibly increase risk of infection, hypersensitivity, or autoimmune issues for exploration astronauts.”

However, despite the discovery of these changes to the immune system, it is not yet known if this phenomenon increases medical issues during spaceflight. Dr. Crucian said that additional research will be needed to precisely assess the potential increased clinical risk to crew members on missions with longer durations.

“Once these investigations are complete, Crucian expects the agency will have a decision point for establishing countermeasures that it must then decide how to implement. If deemed necessary, countermeasures for immunity could include new types of radiation shielding, nutritional supplementation, pharmaceuticals and more,” NASA concluded.